Pump and motor hydraulic system



P 14, 1954 R. E. VON RUDEN PUMP AND MOTOR HYDRAULIC SYSTEM 2Sheets-Sheet 1 Filed Sept. 19, 1951 p 14, 1954 R. E. VON RUDEN 2,688,846

PUMP AND MOTOR HYDRAULIC SYSTEM Filed Sept. 19, 1951 2 Sheets-Sheet 2 II I I I IN V EN TOR.

@WMJ. 7622M BY WM ,47 7 ORA/f VJ Patented Sept. 14, 1954 UNITEDSTATESPATENT OFFICE 2 Claims.

My invention relates generally to fluid pressure apparatus and morespecifically to fluid pressure systems and pump structure therefor.

More particularly, my invention relates to improvements in a so-calledopen fluid pressure system, that is, the type of system which includes afluid supply tank or reservoir open to atmosphere and from which a pumpreceives fluid for delivery to a fluid pressure motor or the like underrelatively high pressure, from whence said fluid is returned to thereservoir under relatively low pressure. The instant invention utilizesthe advantages of both open and closed types of fluid pressure systemsto obtain maximum efficiency with a minimum of loss due to friction orheat.

An important object of my invention is the provision of means, in afluid pressure system having driving and driven elements, whereby aportion of the fluid discharged from the driven element is returneddirectly to the driving element for recirculation therethrough.

Another object of my invention is the provision of novel means forintroducing fluid to a pump in a fluid pressure system.

Another object of my invention is the provision of a pump having inletand discharge passages each communicating with an impeller chamber, oneend portion of said inlet passage being angularly disposed with respectto the other end portion thereof, and means for introducing fluid to theinner end of said inlet passage in a direction axially thereto, wherebyVenturi action is obtained. 7

Still another object of my invention is the provision of a pump for afluid pressure system of the above type which is relatively simple andinexpensive to produce, which is eflicient in operation, and which isrugged in construction and durable in use.

Other highly important objects and advantages of my invention willbecome apparent from the following detailed specification, appendedclaims, and attached drawings.

Referring to the drawings which illustrate the invention and in whichlike characters indicate like parts throughout the several views:

Fig. 1 is a view partly in side elevation and partly diagrammatic of afluid pressure system built in accordance with my invention andincorporating my novel pump;

Fig. 2 is a top plan view of the pump of my invention on an enlargedscale; and

Fig. 3 is a vertical section taken on the line 3-3 of Fig. 2.

In the preferred embodiment of my invention reservoir l, a pump 2, afluid pressure operated motor 3 and conduit means hereinafter described.The fluid pressure motor 3 is conventional in nature and may be of anyone of a number of types commonly used as driven elements in a fluidpressure system. For the purpose of the present example, it may beassumed that the motor 3 comprises a pair of intermeshing spur gears,not shown but mounted one each on one of a pair of shafts 4 and 5journalled in the motor casing identified by the numeral 6. A conduit isconnected to the inlet 8 of the motor 3, the discharge 9 of the motorbeing coupled to a conduit, indicated by a broken line I8, by means of asuitable fitting such as an elbow II. Either of the shafts 4 or 5 may beextended laterally outwardly of the motor casing 6 to provide powertake-01f means.

The pump 2 includes a casing having a main body l2 and a pair of opposedcover elements or plates l3 and I4 one each rigidly secured to anopposite side of the main body I2 by means of machine screws or the likel5. Said body and cover plates define a chamber l6 which contains a pairof intermeshing spur gears l1 and 18 that are keyed or otherwiseanchored to laterally spaced parallel shafts l9 and 20 respectivelyjournalled in spaced bearing bosses 2| integrally formed with respectivecover plates l3 and 14. One of the shafts, as shown the shaft I9,extends laterally outwardly of the cover plate [4 and is adapted to becoupled to a source of rotary power to operate the pump 2.

The pump 2 is provided with inlet and outlet passages 22 and 23respectively each communieating with the chamber IS. The inlet passage22 at its inner end 24 adjacent the chamber i6 is angularly disposedwith respect to its outer end portion 25. As indicated in Fig. 1, theconduit l is connected to the discharge passage 23 by suitable meanssuch as a pipe fitting in the nature of an elbow 26, and a conduit 2!extends from the supply tank or reservoir I to the outer end 25 of theinlet passage 22. As also indicated in Fig. 1, a portion of the conduit21 is indicated by broken lines.

The main body -l2 of the pump 2 is formed to provide a duct 28 whichextends therethrough in spaced relation to the inlet passage 22, saidduct having an inlet port 29 and an outlet port 30. The conduit I0extendingfrom the discharge of the fluid motor 3 is connected to theinlet port 29 by means of a pipe fitting in the nature of an elbow 3|whereas the outlet end or port 30 of the duct 28 has screw-threadedtherein a return conduit 32 which extends to the reservoir I, asindicated by broken lines in Fig. 1.

The above-described apparatus provides a fluid pressure system of theso-called open type wherein all of the fluid pumped to and through themotor 3 by the pump 2 is returned to the reservoir I. The open typesystem is advantageous, in one respect, in that the fluid returned tothe reservoir has a chance to lose some of the heat of frictionresulting from its circulation through the pump and motor and theconnecting conduits therefor before it is recirculated. However, thistype of system is at a distinct disad vantage over the closed systemwherein fluid discharged from the motor is returned directly to theinlet of the pump, in that an appreciable amount of power is consumed bythe pump in drawing fluid from the supply tank or reservoir,particularly when the reservoir is located at some distance from thepump and at a level therebelow. Ina normal closed system, difficulty isoften experienced in maintaining a relatively cool temperature of thefluid and in preventing the same from foaming or becoming excessivelyaerated. To utilize the advantages of both systerns, and to avoid thedisadvantages thereof, I provide shunt means in the nature of a shunt orbranch passage 33 extending from the duct 28 to the inlet passage 22within the main body l2 of the pump. With particular reference to Fig.3, it will be seen that the shunt passage 33 is axially aligned with thinner end portion 2d of the inlet passage 22. It will also be noted thatthe shunt passage 33 is of smaller cross-section than is the passage 22.In practice, the passage 33 has a cross-sectional area which is lessthan one-half the cross-sectional area of the passage 22.

In operation, rotary movement imparted to the intermeshing spur gears ITand iii, in directions indicated by the arrows thereon in Fig. 3, willcause fluid to be drawn into the chamber $6 from the reservoir 1 throughthe inlet 22 and forced outwardly of the discharge passage 23 to andthrough the motor 3 to impart rotary movement to the shafts 4 and 5thereof. Fluid discharged from the motor 3 is returned to the duct 28under pressure through the conduit iii, a portion of said fluid enteringthe inlet passage 22 through the shunt passage 33. The passage 33 beingof insuflicient size to carry the entire amount of fluid under pressuredelivered to the inlet of the duct 28 from the motor 3 the remainder ofthe fluid in the duct '28 returns to the reservoir I through the conduit32. Since a pressure is required to return the fluid from the motor 3 tothe reservoir I a pressure is built up in the duct 28. The fluidentering the passage 22 is under relatively'low pressure and is drawntoward the chamber l6 through the shunt passage 33 which is directedacross the passage 22 toward the pump gears ll, H3 at the inlet side ofchamber l6 forming a jet action across the passage 22 and creating aVenturi action therein. Such active supplements the negative pressure inthe inlet passage 22 created by the suction of the pump gears l'I-IB,thus reducing the possibility of cavitation at the pump inlet andmaterially increasing the efiiciency of the pump by assisting in keepingthe inlet passage 24 completely filled with liquid. Part of the fluid inthe conduit It] returns to the reservoir I, the remainder thereof beingrecirculated through the pump 2 and the motor 3. The fluid movingthrough the shunt passage 33 is cooled by the fluid entering the inletpassage 22 from the conduit 21 while at the same time increasing theefficiency of the pump by overcoming to an appreciable extent the powerloss suifered by the pump in drawing fluid from the supply tank I.Moreover, when the pump has been idle for a period of time, sufficientfluid remains in the duct 28 as well as in the inlet passage 22 toobviate the necessity of priming the pump 2 when it is again desired tooperate the same.

In practice, I have found that greatly increased efiiciency has beenobtained in driving fluid pressure operated motors with my invention inthe manner above described. In fact, by use of my novel arrangement, Ihave been able to triple the speed of the motor without increasing thespeed of the pump, and heating of the fluid du to friction in thevarious component elements of the system has been kept to a minimum.

While I have shown and described a preferred embodiment of my novelfluid pressure system and pump therefor, it will be understood that thesame is capable of modification and that modification may be madewithout departure from the spirit and scope of the invention, as definedin the claims.

What I claim is:

l. A fluid pressure system comprising a pump having a housing defining achamber having impeller means therein and inlet and outlet passagescommunicating with said chamber, a fluid pressure operated motor havingan inlet and an outlet, a fluid conduit connecting the outlet pa sage ofsaid pump to the inlet of said motor, a fluid reservoir, a conduitdelivering fluid from said reservoir to the inlet passage of said pump,said housing further defining a duct having an inlet and an outlet, aconduit connecting the outlet of said motor to the inlet of said duct,conduit means connecting the outlet of said duct to the reservoir, saidinlet passage to the pump chamber having a restricted portion and anexpanded portion, said expanded portion being adjacent the pump chamberand angularly disposed with re" spect to said restricted portion, saidhousing further defining a shunt passage communicating with said ductand the expanded portion of said inlet passage, said shunt passage beingin alignment with said expanded portion, the total cross sectional areaof said shunt passage being of insufiicient size to carry the fullamount of the fluid delivered to the intake of said duct thus creating apositive pressure in the duct, the fluid under the positivepressure-entering the expanded portion of said inlet passage throughsaid duct and shunt passage and across said inlet at a predeterminedspeed of the pumping movement of said impeller means and cooperatingwith said impeller means to create relatively high negative pressure inthe restricted portion of said inlet passage.

2. The structure defined in claim 1, wherein the shunt passage has asmaller cross sectional area than said inlet passage.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 985,986 Eisermann Mar. 7, 1911 2,056,994 Woods Oct. 13, 19362,343,486 Stepanoff Mar. '7, i944 FOREIGN PATENTS Number Country Date361,823 Germany Oct. 19, 1922 234,209 Great Britain May 28, 1925

